In the current thin film transistor liquid crystal display (TFT-LCD) industry, a narrow frame configuration has become a trend. In order to achieve a narrow frame, it is necessary to reduce the area occupied by peripheral circuits outside the pixel region as much as possible, and the most common used method is to employ gate-driver-on-array (GOA) technology. The GOA technology involves preparing gate driving circuits on an array substrate, and thus externally connected gate driving integral circuits can be omitted. But GOA units need a number of via holes and transparent electrodes for connecting circuit lines formed by a gate metal layer and circuit lines formed by a source/drain metal layer, which will occupy a large area and thus the narrow frame of the thin film transistor liquid crystal display cannot be minimized.